
<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml" lang="zh_CN">
  <head>
    <meta charset="utf-8" />
    <title>平台支持 &#8212; Python 3.7.8 文档</title>
    <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
    <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
    
    <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
    <script type="text/javascript" src="../_static/jquery.js"></script>
    <script type="text/javascript" src="../_static/underscore.js"></script>
    <script type="text/javascript" src="../_static/doctools.js"></script>
    <script type="text/javascript" src="../_static/language_data.js"></script>
    <script type="text/javascript" src="../_static/translations.js"></script>
    
    <script type="text/javascript" src="../_static/sidebar.js"></script>
    
    <link rel="search" type="application/opensearchdescription+xml"
          title="在 Python 3.7.8 文档 中搜索"
          href="../_static/opensearch.xml"/>
    <link rel="author" title="关于这些文档" href="../about.html" />
    <link rel="index" title="索引" href="../genindex.html" />
    <link rel="search" title="搜索" href="../search.html" />
    <link rel="copyright" title="版权所有" href="../copyright.html" />
    <link rel="next" title="高级API索引" href="asyncio-api-index.html" />
    <link rel="prev" title="策略" href="asyncio-policy.html" />
    <link rel="shortcut icon" type="image/png" href="../_static/py.png" />
    <link rel="canonical" href="https://docs.python.org/3/library/asyncio-platforms.html" />
    
    <script type="text/javascript" src="../_static/copybutton.js"></script>
    
    
    
    
    <style>
      @media only screen {
        table.full-width-table {
            width: 100%;
        }
      }
    </style>
 

  </head><body>
  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>导航</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="总目录"
             accesskey="I">索引</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python 模块索引"
             >模块</a> |</li>
        <li class="right" >
          <a href="asyncio-api-index.html" title="高级API索引"
             accesskey="N">下一页</a> |</li>
        <li class="right" >
          <a href="asyncio-policy.html" title="策略"
             accesskey="P">上一页</a> |</li>
        <li><img src="../_static/py.png" alt=""
                 style="vertical-align: middle; margin-top: -1px"/></li>
        <li><a href="https://www.python.org/">Python</a> &#187;</li>
        <li>
          <a href="../index.html">3.7.8 Documentation</a> &#187;
        </li>

          <li class="nav-item nav-item-1"><a href="index.html" >Python 标准库</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="ipc.html" >网络和进程间通信</a> &#187;</li>
          <li class="nav-item nav-item-3"><a href="asyncio.html" accesskey="U"><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> --- 异步 I/O</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="快速搜索" type="text" name="q" />
          <input type="submit" value="转向" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>    

    <div class="document">
      <div class="documentwrapper">
        <div class="bodywrapper">
          <div class="body" role="main">
            
  <div class="section" id="platform-support">
<span id="asyncio-platform-support"></span><h1>平台支持<a class="headerlink" href="#platform-support" title="永久链接至标题">¶</a></h1>
<p><a class="reference internal" href="asyncio.html#module-asyncio" title="asyncio: Asynchronous I/O."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code></a> 模块被设计为可移植的,但由于平台的底层架构和功能，一些平台存在细微的差异和限制。</p>
<div class="section" id="all-platforms">
<h2>所有平台<a class="headerlink" href="#all-platforms" title="永久链接至标题">¶</a></h2>
<ul class="simple">
<li><p><a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_reader" title="asyncio.loop.add_reader"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_reader()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_writer" title="asyncio.loop.add_writer"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_writer()</span></code></a> 不能用来监视文件I/O。</p></li>
</ul>
</div>
<div class="section" id="windows">
<h2>Windows<a class="headerlink" href="#windows" title="永久链接至标题">¶</a></h2>
<p>Windows上的所有事件循环都不支持以下方法:</p>
<ul class="simple">
<li><p>不支持 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_unix_connection" title="asyncio.loop.create_unix_connection"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_unix_connection()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_unix_server" title="asyncio.loop.create_unix_server"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_unix_server()</span></code></a> 。 <a class="reference internal" href="socket.html#socket.AF_UNIX" title="socket.AF_UNIX"><code class="xref py py-data docutils literal notranslate"><span class="pre">socket.AF_UNIX</span></code></a> 套接字相关参数仅限于Unix。</p></li>
<li><p>不支持 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_signal_handler" title="asyncio.loop.add_signal_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_signal_handler()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.remove_signal_handler" title="asyncio.loop.remove_signal_handler"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.remove_signal_handler()</span></code></a> 。</p></li>
</ul>
<p><a class="reference internal" href="asyncio-eventloop.html#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> 有下列限制:</p>
<ul class="simple">
<li><p><a class="reference internal" href="selectors.html#selectors.SelectSelector" title="selectors.SelectSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectSelector</span></code></a> 只被用于等待套接字事件：它支持套接字且最多支持512个套接字。</p></li>
<li><p><a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_reader" title="asyncio.loop.add_reader"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_reader()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_writer" title="asyncio.loop.add_writer"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_writer()</span></code></a> 只接受套接字处理回调函数(如管道、文件描述符等都不支持)。</p></li>
<li><p>因为不支持管道，所以  <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_read_pipe" title="asyncio.loop.connect_read_pipe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.connect_read_pipe()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_write_pipe" title="asyncio.loop.connect_write_pipe"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.connect_write_pipe()</span></code></a> 方法没有实现。</p></li>
<li><p>不支持 <a class="reference internal" href="asyncio-subprocess.html#asyncio-subprocess"><span class="std std-ref">Subprocesses</span></a> ，也就是  <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_exec" title="asyncio.loop.subprocess_exec"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.subprocess_exec()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_shell" title="asyncio.loop.subprocess_shell"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.subprocess_shell()</span></code></a> 方法没有实现。</p></li>
</ul>
<p><a class="reference internal" href="asyncio-eventloop.html#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> 有下列限制:</p>
<ul class="simple">
<li><p>不支持 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_datagram_endpoint" title="asyncio.loop.create_datagram_endpoint"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.create_datagram_endpoint()</span></code></a> 方法。</p></li>
<li><p>不支持  <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_reader" title="asyncio.loop.add_reader"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_reader()</span></code></a> 和 <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.add_writer" title="asyncio.loop.add_writer"><code class="xref py py-meth docutils literal notranslate"><span class="pre">loop.add_writer()</span></code></a> 方法。</p></li>
</ul>
<p>Windows上单调时钟的分辨率大约为 15.6 毫秒。最佳的分辨率是 0.5 毫秒。分辨率依赖于具体的硬件（<a class="reference external" href="https://zh.wikipedia.org/wiki/高精度事件计时器">HPET</a>）和Windows的设置。</p>
<div class="section" id="subprocess-support-on-windows">
<span id="asyncio-windows-subprocess"></span><h3>Windows的子进程支持<a class="headerlink" href="#subprocess-support-on-windows" title="永久链接至标题">¶</a></h3>
<p>Windows上的 <a class="reference internal" href="asyncio-eventloop.html#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> 不支持子进程，使用 <a class="reference internal" href="asyncio-eventloop.html#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> 代替它:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>

<span class="n">asyncio</span><span class="o">.</span><span class="n">set_event_loop_policy</span><span class="p">(</span>
    <span class="n">asyncio</span><span class="o">.</span><span class="n">WindowsProactorEventLoopPolicy</span><span class="p">())</span>

<span class="n">asyncio</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">your_code</span><span class="p">())</span>
</pre></div>
</div>
<p>也不支持 <a class="reference internal" href="asyncio-policy.html#asyncio.AbstractEventLoopPolicy.set_child_watcher" title="asyncio.AbstractEventLoopPolicy.set_child_watcher"><code class="xref py py-meth docutils literal notranslate"><span class="pre">policy.set_child_watcher()</span></code></a> 函数，<a class="reference internal" href="asyncio-eventloop.html#asyncio.ProactorEventLoop" title="asyncio.ProactorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">ProactorEventLoop</span></code></a> 有不同的机制来监视子进程。</p>
</div>
</div>
<div class="section" id="macos">
<h2>macOS<a class="headerlink" href="#macos" title="永久链接至标题">¶</a></h2>
<p>完整支持流行的macOS版本。</p>
<p class="rubric">macOS &lt;= 10.8</p>
<p>在 macOS 10.6, 10.7 和 10.8 上，默认的事件循环使用 <a class="reference internal" href="selectors.html#selectors.KqueueSelector" title="selectors.KqueueSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">selectors.KqueueSelector</span></code></a>，在这些版本上它并不支持字符设备。 可以手工配置 <a class="reference internal" href="asyncio-eventloop.html#asyncio.SelectorEventLoop" title="asyncio.SelectorEventLoop"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorEventLoop</span></code></a> 来使用 <a class="reference internal" href="selectors.html#selectors.SelectSelector" title="selectors.SelectSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectSelector</span></code></a> 或 <a class="reference internal" href="selectors.html#selectors.PollSelector" title="selectors.PollSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">PollSelector</span></code></a> 以在这些较老版本的 macOS 上支持字符设备。 例如:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">asyncio</span>
<span class="kn">import</span> <span class="nn">selectors</span>

<span class="n">selector</span> <span class="o">=</span> <span class="n">selectors</span><span class="o">.</span><span class="n">SelectSelector</span><span class="p">()</span>
<span class="n">loop</span> <span class="o">=</span> <span class="n">asyncio</span><span class="o">.</span><span class="n">SelectorEventLoop</span><span class="p">(</span><span class="n">selector</span><span class="p">)</span>
<span class="n">asyncio</span><span class="o">.</span><span class="n">set_event_loop</span><span class="p">(</span><span class="n">loop</span><span class="p">)</span>
</pre></div>
</div>
</div>
</div>


          </div>
        </div>
      </div>
      <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
        <div class="sphinxsidebarwrapper">
  <h3><a href="../contents.html">目录</a></h3>
  <ul>
<li><a class="reference internal" href="#">平台支持</a><ul>
<li><a class="reference internal" href="#all-platforms">所有平台</a></li>
<li><a class="reference internal" href="#windows">Windows</a><ul>
<li><a class="reference internal" href="#subprocess-support-on-windows">Windows的子进程支持</a></li>
</ul>
</li>
<li><a class="reference internal" href="#macos">macOS</a></li>
</ul>
</li>
</ul>

  <h4>上一个主题</h4>
  <p class="topless"><a href="asyncio-policy.html"
                        title="上一章">策略</a></p>
  <h4>下一个主题</h4>
  <p class="topless"><a href="asyncio-api-index.html"
                        title="下一章">高级API索引</a></p>
  <div role="note" aria-label="source link">
    <h3>本页</h3>
    <ul class="this-page-menu">
      <li><a href="../bugs.html">提交 Bug</a></li>
      <li>
        <a href="https://github.com/python/cpython/blob/3.7/Doc/library/asyncio-platforms.rst"
            rel="nofollow">显示源代码
        </a>
      </li>
    </ul>
  </div>
        </div>
      </div>
      <div class="clearer"></div>
    </div>  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>导航</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="总目录"
             >索引</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python 模块索引"
             >模块</a> |</li>
        <li class="right" >
          <a href="asyncio-api-index.html" title="高级API索引"
             >下一页</a> |</li>
        <li class="right" >
          <a href="asyncio-policy.html" title="策略"
             >上一页</a> |</li>
        <li><img src="../_static/py.png" alt=""
                 style="vertical-align: middle; margin-top: -1px"/></li>
        <li><a href="https://www.python.org/">Python</a> &#187;</li>
        <li>
          <a href="../index.html">3.7.8 Documentation</a> &#187;
        </li>

          <li class="nav-item nav-item-1"><a href="index.html" >Python 标准库</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="ipc.html" >网络和进程间通信</a> &#187;</li>
          <li class="nav-item nav-item-3"><a href="asyncio.html" ><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code> --- 异步 I/O</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="快速搜索" type="text" name="q" />
          <input type="submit" value="转向" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>  
    <div class="footer">
    &copy; <a href="../copyright.html">版权所有</a> 2001-2020, Python Software Foundation.
    <br />
    Python 软件基金会是一个非盈利组织。
    <a href="https://www.python.org/psf/donations/">请捐助。</a>
    <br />
    最后更新于 6月 29, 2020.
    <a href="../bugs.html">发现了问题</a>？
    <br />
    使用<a href="http://sphinx.pocoo.org/">Sphinx</a>2.3.1 创建。
    </div>

  </body>
</html>